Crazy Boy switched on the left indicator and moved over to the inside lane, preparing to leave the motorway. ‘Why aren’t we going straight to London?’ asked Two Knives. He had a bag of khat on his lap and he spoke through a mouthful of leaves.

‘The Arab said it has to be checked first. There’s no point if it doesn’t go off. Everything will have been wasted.’ He reached over and helped himself to a handful of khat. ‘Don’t worry, we won’t be staying long.’

The two men had port IDs clipped to their overalls. The IDs and the truck had been supplied by al-Zahrani, along with the necessary paperwork to collect the container from the Athena. The container had been one of the first to be unloaded and Crazy Boy was sure that hadn’t been a coincidence. Al-Zahrani seemed to have planned everything to perfection.

A surveillance video flashed up on to one of the monitors. Button walked over to it and pointed at a truck driving out of Southampton Container Terminal. On the back of the truck was a dark green container. ‘There it is,’ she said.

The operator looped the video so that it replayed several times.

‘Right,’ said Button, standing up. ‘We have now received confirmation that the green container at the stern was not on the ship when it left Port Klang in Malaysia. It was also not loaded at Karachi or Jeddah, but was on board when the Athena arrived at Southampton. We can only assume that it was taken to the ship by helicopter while the Athena was under the control of the pirates. The question is, where is it now?’

‘GPS?’ said one of the technicians. ‘A lot of containers have GPS so they can be tracked by their owners.’

Button shook her head. ‘The registration number of the container doesn’t match any on record so we can’t trace its owner. It doesn’t exist officially.’

She nodded at the technician and a close-up still shot of the truck’s number plate appeared on another screen. ‘We have the registration number of the truck and again it’s a ringer. The vehicle belonging to that plate is on the Continent as we speak. But at least we have something to go on. We’re currently running the number through every CCTV database we’ve got and every police force in the country is on the lookout for it.’

There was a knock on the door and a man in his sixties with slicked-back grey hair and wearing a tweed suit appeared. ‘Dr Wilson,’ he said. Button nodded at him. ‘Dr Wilson sits on the London Fire and Emergency Planning Authority and is something of an expert on nuclear- and radiation-based incidents,’ she said by way of introduction. ‘I thought we might all benefit from a quick rundown on what we might be facing here.’